The railroad industry has made a number of attempts to provide alternative power sources for powering locomotives, such as railyard switching locomotives and over-the-road (i.e., long haul freight transport) locomotives. Such alternatives seek to reduce or eliminate the reliance on the production of power by combustion of fossil fuel, typically diesel fuel, and the resulting emissions.
The typical locomotive includes an internal combustion diesel engine that powers an AC generator, which in turn is coupled to an AC-DC rectifier to output a DC current. The DC current is delivered to a bus, which distributes the power to individual electric motors (referred to as traction motors) that drive the track engaging wheels of the locomotive. There have also been designs using a DC power generator, which does not require the use of a rectifier. In either approach, the electrical power used to operate the locomotive is generated by the operation of the generator by the engine, which combusts diesel fuel to generate power. This generates unwanted emissions discharged into the atmosphere. Also, fuel costs constitute a significant percentage of a locomotive's operating costs, and fluctuations of fuel costs can have a significant impact on railroad operations.
There are variety of patents related to using electrochemical power sources, such as batteries, to power locomotives. For example, U.S. Patent Application Publication 2007/0272116 A1 to Bartley et al. discloses a hybrid diesel electric-powered locomotive with electrically propelled locomotives and battery cars. The battery cars contain a battery pack which are charged via regenerative braking when the train is descending down a hill. The cars and locomotives are used to provide additional electric power to assist in moving the train uphill.
U.S. Pat. No. 6,308,639 B1 to Donnelly et al. describes a battery for supplying electric energy to traction motors of a locomotive. The battery is periodically charged by a microturbine generator.
U.S. Pat. No. 6,689,507 B1 to Tsutsumi et al. shows in FIG. 38(a) an electric locomotive connected to a power vehicle containing an engine electric generator and a three-dimensional battery therein (see, e.g., column 44, lines 11-60).
U.S. Pat. No. 7,430,967 B2 and U.S. Patent Application Publication 2008/0270023 A1 both to Kumar each discloses a hybrid energy locomotive system with an energy tender vehicle coupled to a locomotive for capturing and regenerating at least a portion of the braking electric energy generated while the locomotive is operated. Alternatively, the energy capture and storage system can be charged by a diesel generator, or by a battery charger at a train yard, for example. The system may be used to drive the traction motors of the locomotive. The system may be connected to the power grid as well.
Indeed, U.S. Pat. No. 1,424,849 evidences efforts at making a locomotive powered by an electrochemical power source (e.g., a battery) dating as far back as 1917 (the patent's filing date).
The present invention endeavors to provide an alternative power source that can store significant amounts of energy and can be easily replaced or recharged.